Skin cancer is among the top 10 most common cancers in Singapore, coming in six amongst the Singapore population. While most people do not die from skin cancer, it is a disease that should not be taken lightly. In this article, Dr. Melissa Tan Wee Ping, Senior Consultant Dermatologist and Dermatologic Surgeon, talks about the ABCDE's of skin cancer.
The skin is the body’s largest organ and the only organ that we can see, feel, and touch. As our skin is our body’s protection from the external environment, problems such as injuries, inflammatory rashes, ageing, and even skin cancers can occur.
“Practically every single cell in our skin has the potential of developing into skin cancer and they can range from common ones like basal cell carcinoma, squamous cell carcinoma, to less common but equally important skin cancers like melanoma, and rare ones like sebaceous carcinoma and angiosarcoma. ” Dr. Tan said.
But not all rash or a lump is cancerous.
"Whenever you are faced with a rash or a lump, you have to decide if it is a form of skin tumor. Once the diagnosis of skin tumor is made, it is then important to confirm if it is a benign or malignant neoplasm. If a skin tumor is suspected, patients should be referred to a dermatologist for further assessment and evaluation. Most of the time, a skin biopsy will be necessary to confirm the diagnosis.”
Regular skin cancer screening checks are also recommended for patients at high risk of skin cancers. Some risk factors for skin cancers include light skin colour with tendency to sunburn, multiple moles on the body, and personal history of skin cancer. During this, a thorough skin check with dermatoscopic assessment of moles and growths on the body is performed.
Basal cell carcinomas (BCC) are the most common form of skin cancer in Singapore and worldwide. Squamous cell carcinomas (SCC) are the next most common. By comparison, melanomas are less common, but nonetheless very important.
"Although the incidence of melanoma in Singapore is relatively low, melanoma causes most of the deaths from skin cancer,” Dr Tan said.
According to a research paper that Dr. Tan co-authored, there is a long lag time to presentation, resulting in the delay in diagnosis of melanoma for the Asian population in Singapore1. The study also found that only two thirds of lesions were clinically suspected to be malignant melanoma at initial presentation, highlighting the importance of a vigilant physical examination and a high index of suspicion.
Besides in-clinic skin screening, it is also pertinent to educate patients on the importance of regular self- checks at home.
The ABCDE rule can guide patients when performing self checks
Dr. Tan cautioned that while the ABCDE guide is good self-examination, it is still capable of going wrong.
“Many common benign lesions such as seborrheic keratosis, lentigines and warts can screen positive for possible melanoma with the ABCDE rule. Conversely, a lesion that looks regular can turn out to be a melanoma,” she added.
To mitigate this, the ‘Ugly Duckling Sign’ can be used to detect suspicious lesions.
“The premise for this concept is that on any individual, moles tend to resemble one another, and so if you have one mole or spot that stands out as very different from the rest, it is important to pay attention to it,” Dr. Tan explained.
“Some types of skin cancers, like Bowen’s disease or mycosis fungoides, can look like psoriasis or discoid eczema. In a busy outpatient clinic, patients are usually prescribed topical medicine for treatment. However, it is important to go back for a review to make sure the rash actually goes away. If it does not, then it is advisable to consult a dermatologist,” she said.
Acral lentiginous melanoma is the most common form of melanoma among Asians in Singapore. “About 44 per cent of the melanomas in the Asian population in our study occurred in the acral region and the most common site of presentation was on the sole of the foot,” she added.
It can also occur under the nail which is known as subungual melanoma. It usually presents itself as a light- to dark-brown vertical pigmentation. However, it is usually more common in an older person and surfaces during the fifth to seventh decade of life. The condition is not common in children.
“If the pigmentation extends beyond the nail fold onto the skin around the nail, it is called a Hutchinson's sign,” Dr. Tan explained.
Most skin cancers can be cured by surgical excision. A specialised form of skin surgery to remove high risk BCC and SCC is Mohs micrographic surgery.
Sometimes, surgery may not be possible, and radiotherapy may be a more suitable alternative. Some superficial skin cancers may not need surgical treatment and can be managed by other non-surgical methods. This may involve cryotherapy with liquid nitrogen, topical therapy (creams) or photodynamic therapy.2